Allow floatfoot to left-align beneath figure, but extend past right

Question

I can set my \caption and my \floatfoot as separate widths, using the following example, based on the answer to my previous question: Different width for caption and floatfoot with floatrow

\documentclass{article}
\usepackage{floatrow}
\usepackage[demo]{graphicx}
\usepackage{siunitx}
\usepackage{caption}

\begin{document}

\begin{figure}
\RawCaption%
    {\caption{Selected Interatomic Distances of Protons in $\beta$-Pinene Normal Lactone}%
     \label{fig:noeDistances}}\vskip\captionskip
\floatbox[{\captop}]{figure}[\FBwidth]
    {}
    {\includegraphics{nOeDistances}
    \floatfoot{\textsuperscript{1}All distances reported are in \si{\angstrom}.%
    \\ \textsuperscript{2}Selected carbon numbering is given in cyan.}}
\end{figure}

\end{document}

However, I've found that in this case the second footnote wraps because the figure width is quite small. The result I had intended to achieve, would be that the \floatfoot would be left aligned to the figure, but be able to extend past the right of the figure.

I did try setting the width of the \floatbox to something greater than \FBwidth using the calc package, and then use \FBwidth*\real{1.5}, but this predictably puts half the extra space on each side of the float. Resulting in the \floatfoot no longer being left-aligned.

I've also considered manually calculating the width of the image, then setting the margins myself, something like:

\def\mygraphic{\includegraphics{nOeDistances}}
\newlength\graphicwidth
\setlength\graphicwidth{\widthof{\mygraphic}}
\newlength\leftMarg
\newlength\rightMarg
\setlength\leftMarg{\textwidth-\graphicwidth/2}
\setlength\rightMarg{0pt}

But I'm just not familiar enough to complete the idea.

Answer 1

This is a solution I really don't like, but (as I said in a comment) I will post it since no one else has provided a better approach.

The idea is to set the \floatbox width to something greater than \FBwidth and then manually (this is the part I don't like) correcting the alignment for the \floatfoot material.

\documentclass{article}
\usepackage{floatrow}
\usepackage[demo]{graphicx}
\usepackage{siunitx}
\usepackage{caption}

% a length to store the current \FBwidh value for latter use
\newlength\mylena

\begin{document}

\begin{figure}
\RawCaption%
    {\caption{Selected Interatomic Distances of Protons in $\beta$-Pinene Normal Lactone}%
     \label{fig:noeDistances}}\vskip\captionskip
\floatbox[{\captop}]{figure}[1.4\FBwidth\setlength\mylena\FBwidth]
    {}
    {\includegraphics{nOeDistances}
    \floatfoot{\hspace*{0.15\mylena}\textsuperscript{1}All distances reported are in \si{\angstrom}.%
    \hfill\null\\\hspace*{0.15\mylena}\textsuperscript{2}Selected carbon numbering is given in cyan.}}
\end{figure}

\end{document}